U.S. patent number 7,712,315 [Application Number 11/407,668] was granted by the patent office on 2010-05-11 for augmentor variable vane flame stabilization.
This patent grant is currently assigned to United Technologies Corporation. Invention is credited to Donald J. Hautman, Derk S. Philippona.
United States Patent |
7,712,315 |
Hautman , et al. |
May 11, 2010 |
Augmentor variable vane flame stabilization
Abstract
A flameholder for an augmentor rotates about an axis radially
positioned with a turbine engine. The flameholder is in a
streamlined position when the augmentor is not operating to
minimize pressure loss and radar cross-section and a turbulent
position when the augmentor is operating. A linkage connects the
flameholder to an actuator to control the rotational position of
the flameholder on the axis. Bypass airflow from the fan cools the
flameholders and linkages. The length of the linkages can be varied
from one flameholder to another to create asymmetric heat release
within the augmentor to avoid screech.
Inventors: |
Hautman; Donald J.
(Marlborough, CT), Philippona; Derk S. (Tolland, CT) |
Assignee: |
United Technologies Corporation
(Hartford, CT)
|
Family
ID: |
38618153 |
Appl.
No.: |
11/407,668 |
Filed: |
April 20, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20070245743 A1 |
Oct 25, 2007 |
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Current U.S.
Class: |
60/763;
60/765 |
Current CPC
Class: |
F23R
3/20 (20130101); F02K 3/10 (20130101) |
Current International
Class: |
F02K
3/10 (20060101) |
Field of
Search: |
;60/761-766 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Cuff; Michael
Assistant Examiner: Wongwian; Phutthiwat
Attorney, Agent or Firm: Carlson, Gaskey & Olds
Claims
What is claimed is:
1. A turbine engine comprising: a turbine exhaust inner case and a
turbine exhaust outer case spaced radially outwardly relative to
the turbine exhaust inner case and radially inwardly of an engine
outer case; a plurality of fuel spraybars circumferentially spaced
apart from each other about the turbine exhaust inner case and
extending in a radial direction from the turbine exhaust inner case
to the turbine exhaust outer case, wherein each fuel spraybar is
housed within a vane; and a flameholder associated with each of the
plurality of fuel spraybars, wherein each flameholder is movable;
an actuator linkage connecting an actuator to the flameholders; and
a cooling air supply for the flameholders and the actuator
linkage.
2. The turbine engine of claim 1, wherein each flameholder is
positioned aft of the associated fuel spraybar and vane.
3. The turbine engine of claim 1, wherein each flameholder rotates
about an axis extending radially from the turbine exhaust inner
case to the turbine exhaust outer case.
4. The turbine engine of claim 1, wherein the actuator and at least
a portion of the actuator linkage is located on the turbine engine
outer case.
5. The turbine engine of claim 1, wherein the cooling air supply is
bypass cooling air provided through a bypass duct of the turbine
engine.
6. The turbine engine of claim 1, including a plurality of
actuators for moving the flameholders.
7. The turbine engine of claim 1, where each flameholder is in a
streamlined position when a turbine engine augmentor is not
operating and in a turbulent position when the turbine engine
augmentor is operating.
8. The turbine engine of claim 7, where the turbulent position of
the flameholder is determined based on altitude and speed of an
aircraft.
9. A turbine engine augmentor comprising: a plurality of fuel
spraybars circumferentially spaced about a turbine exhaust inner
case and extending radially outwardly to a turbine exhaust outer
case spaced radially inwardly of an engine outer case, wherein each
fuel spraybar is housed within a vane; and a plurality of
flameholders, wherein one of the plurality of flameholders is
positioned aft of each of the fuel spraybars and associated vane,
and wherein the plurality of flameholders are driven to rotate.
10. The turbine engine augmentor of claim 9, wherein an actuator
drives the plurality of flameholders to rotate about an axis that
extends radially from the turbine exhaust inner case to the turbine
exhaust outer case.
11. The turbine engine augmentor of claim 10, wherein the actuator
is located on the turbine engine outer case.
12. The turbine engine augmentor of claim 9, where the flameholder
is in a streamlined position when the turbine engine augmentor is
not operating and in a turbulent position when the turbine engine
augmentor is operating.
13. The turbine engine augmentor of claim 12, wherein the turbulent
position of the flameholder is determined based on altitude and
speed of an aircraft.
14. The turbine engine augmentor of claim 12, wherein a first
plurality of flameholders is connected to a first actuator for
controlling the rotational position of the first plurality of
flameholders, and a second plurality of flameholders are connected
to a second actuator for controlling the rotational position of the
second plurality of flameholders, and the turbulent position of the
first plurality of flameholders is a different rotational position
than the turbulent position of the second plurality of flameholders
to obtain asymmetric heat release.
15. The turbine engine of claim 1, wherein associated flameholders
and fuel spraybars are generally parallel to each other.
16. The turbine engine of claim 15, wherein each fuel spraybar has
a first end associated with the turbine exhaust inner case and a
second end associated with the turbine exhaust outer case and
wherein each fuel spray bar is inclined such that the second end is
positioned aft of the first end.
17. The turbine engine of claim 2, wherein associated vanes,
flameholders, and fuel spraybars each extend from the turbine
exhaust inner case to the turbine exhaust outer case and are
generally parallel to each other.
18. The turbine engine of claim 1, wherein each fuel spraybar
includes a plurality of openings to spray fuel out of the vane and
toward the flameholder.
19. The turbine engine augmentor of claim 9, wherein each fuel
spraybar has a first end associated with the turbine exhaust inner
case and a second end associated with the turbine exhaust outer
case and wherein each fuel spray bar is inclined such that the
second end is positioned aft of the first end.
20. The turbine engine augmentor of claim 9, wherein the vanes
extend radially from the turbine exhaust inner case to the turbine
exhaust outer case, and wherein each fuel spraybar includes a
plurality of openings to spray fuel out of the vane and toward the
flameholder.
21. The turbine engine augmentor of claim 20, wherein associated
vanes, fuel spraybars, and flameholders are generally parallel to
each other.
Description
BACKGROUND OF THE INVENTION
The invention generally relates to an improved arrangement to
provide a variable geometry flameholder in a turbine engine. More
particularly, an inventive flameholder provides a streamlined
geometry when a turbine engine augmentor is not operating and a
"turbulent" geometry when the augmentor is operating.
Turbine engines may have afterburners, or augmentors, located at
the rear of the engine upstream of an exhaust nozzle. Augmentors
utilize unused oxygen from the turbine engine to obtain a second
combustion. The second combustion provides additional thrust from
the turbine engine. An augmentor includes flameholders to create
low velocity wakes to stabilize combustion in the high velocity
turbine engine exhaust.
Flameholders have the disadvantage of creating pressure loss in the
airflow of the turbine engine even when the augmentor is not
operating. The pressure loss when the augmentor is not operating
decreases the thrust of the turbine engine.
Prior turbine engine augmentors have attempted to utilize
flameholders of varying geometry such that the flameholder is
arranged to provide a more streamlined airflow when the augmentor
is not operating. In one known turbine engine, the spraybars and
flameholders were arranged in concentric rings about the inner case
of the turbine engine. Actuators for moving the flameholders were
located within the inner case in order to reach the flameholders.
However, due to the excessive heat within the turbine engine the
components required for varying the flameholder position have had
limited lifespan. Therefore, variable geometry flameholders have
provided limited use in application.
An arrangement to provide a variable geometry flameholder which has
increased durability is needed.
SUMMARY OF THE INVENTION
A variable geometry flameholder for an augmentor according to this
invention is cooled by bypass airflow from a turbine engine.
The augmentor includes vanes radially spaced about the center of
the turbine engine. Each vane houses a spraybar to provide fuel to
mix with leftover oxygen for a second combustion. A flameholder is
located aft of each vane and rotates about an axis also radially
spaced about the center of the turbine engine. A linkage connects
the flameholder to an actuator to control the rotational position
of the flameholder on the axis. Bypass airflow from the fan flows
through the bypass duct of the turbine engine. The bypass airflow
cools the linkages and the surface of the flameholder.
The flameholder is moved to a streamlined position when the
augmentor is not operating and a position to create low velocity
wake when the augmentor is operating. The length of the linkages
are varied from one flameholder to another to vary the amount of
rotation in the augmented positions creating asymmetric heat
release to mitigate or avoid combustion dynamic instabilities or
screech. The actuators and linkages may also be arranged to vary
the rotation the flameholder based upon the aircraft speed and
altitude to obtain the desired combustion stability without
requiring undue actuation force.
The example flameholders of this invention include a variable
geometry while providing increased durability.
These and other features of the present invention can be best
understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a turbine engine with an
augmentor;
FIG. 2 is an end view of the augmenter according to this
invention;
FIG. 3 is a section of the augmentor showing an example vane and
flameholder;
FIG. 4a illustrates a cross-section through the example flameholder
in the streamlined position;
FIG. 4b illustrates a cross-section through the example flameholder
in the turbulent position;
FIG. 5 illustrates a schematic view of a portion of the example
flameholders in utilizing multiple linkages to obtain varying
turbulent positions; and
FIG. 6 illustrates a schematic view of a portion of the example
flameholders utilizing multiple actuators to obtain varying
turbulent positions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a schematic view of a turbine engine 10. Air is pulled
into the turbine engine 10 by a fan 12 and flows through a low
pressure compressor 14 and a high pressure compressor 16. Fuel is
mixed with the oxygen and combustion occurs within the combustor
18. Exhaust from combustion flows through a high pressure turbine
20 and a low pressure turbine 22 prior to leaving the engine
through the exhaust nozzle 24. The example engine 10 includes an
afterburner, or augmentor 26. A turbine exhaust case 28 is located
in front of the exhaust nozzle 24 and behind the low pressure
turbine 22 to house the augmentor 26.
Referring to FIG. 2 an end view of the augmentor 26 looking
upstream into the engine 10 is shown. Air flows into the augmentor
26 at the leading edge 30 and exits at the trailing edge 32. The
augmentor 26 includes vanes 34 positioned between a turbine exhaust
outer case 36 and a turbine exhaust inner case 38. The vanes 34 are
spaced about the turbine exhaust inner case 38. A flameholder 42 is
located aft of each vane 34.
FIG. 3 is a section of the augmentor 26 showing an example vane 34.
The vane 34 is positioned between the turbine exhaust outer case 36
and the turbine exhaust inner case 38. Each vane 34 houses a
spraybar 40 to provide fuel to mix with leftover oxygen for a
second combustion. A spark igniter 48 extends from the turbine
exhaust outer case 36. The spark igniter provides the spark to
begin the second combustion when fuel is expelled from the spraybar
40 and the vane 34.
As shown, the spraybar 40 extends radially within the vane 34
between the turbine exhaust outer case 36 and the turbine exhaust
inner case 38. The flameholder 42 is located aft of the vane 34 and
rotates about an axis A. The axis A is substantially parallel to
the associated spraybar 40 as shown. A linkage 44 connects the
flameholder 42 to an actuator 46. The actuator 46 and the linkage
44 control the rotational position of the flameholder 42 on the
axis A. The other flameholders 42 spaced about the augmentor 26 are
connected to the same or additional linkages 44 and actuators 46 as
explained below. The actuator 46 may be powered by an electric,
hydraulic, or fuel source obtained from another portion of the
turbine engine 10.
Bypass airflow, as indicated by arrow B, from the fan 12 flows
through a bypass duct 66 defined by an engine outer case 68. The
bypass airflow cools the linkages 44. A portion of the bypass
airflow exits the bypass duct 66 and is used to cool the surface of
the flameholder 42. As indicated by arrow B the bypass airflow
enters the interior of the flameholder 42 adjacent to the linkages
44. The interior of the flameholder 42 is hollow to allow airflow
to pass through. Cooling holes are located on the surface of the
flameholder 42 to allow the bypass airflow from the interior of the
flameholder 42 to cool the exterior of the flameholder 42.
In one embodiment the bypass airflow exits the flameholder 42 to
the turbine exhaust inner case 38. From the turbine exhaust inner
case 36 the bypass airflow can also enter the interior of the vanes
34. The bypass airflow cools the vanes 34 and tail cone 72 through
cooling holes formed in the surfaces of the vanes 34 and the tail
cone 72. Bypass airflow that does not enter the flameholder 42
continues through the bypass duct 66 to cool the surface of
augmentor liner 70 through additional cooling holes. The remaining
bypass airflow exits the bypass duct 66 at the end of the augmentor
liner 70 and exits the turbine engine 10 with the exhaust gases
through the nozzle 24.
FIGS. 4a and 4b show a cross-section through the example vane 34
and the flameholder 42 looking from the turbine exhaust inner case
38 toward the turbine exhaust outer case 36. FIG. 4a illustrates
the flameholder 42 in the streamlined position when the augmentor
26 is not operating. FIG. 4b illustrates the flameholder 42 in the
"turbulent" position which is used when the augmentor 26 is
operating. The flameholder 42 is not limited to the triangular
geometry shown. One skilled in the art would be able to design any
geometry which would provide for a streamlined shape to minimize
pressure loss and radar cross section when in the non-augmented
position and a "turbulent" shape in the augment position to achieve
stable combustion.
The spraybar 40 sprays fuel out of the vane 34, as depicted by
arrows F. The spark igniter 48 (shown in FIG. 3) initiates
combustion.
Referring to FIG. 5, asymmetric heat release can also be achieved
by varying the turbulent positions of the flameholders 54 and 56.
The asymmetric heat release avoids exciting the acoustic modes
within the exhaust nozzle 24. Excitation of an acoustic mode
results in a thermo-acoustic phenomena referred to as screech,
which can damage the components of the turbine engine 10.
The turbulent position of the flameholders 54 and 56 is achieved by
the actuator 58 and the linkages 60 and 62. Each flameholder is
attached to the actuator 58 through one of the linkages 60 and 62.
By varying the length of the linkages 60 and 62 from one another
the associate flameholders 54 and 56 vary in position relative to
one another. The amount of rotation between the streamlined
position and the "turbulent" position is varied between flameholder
54 and 56 creating asymmetric airflow within the exhaust nozzle 24.
In this manner a different "turbulent" positions of the
flameholders 54 and 56 may be obtained by replacing the linkages 60
and 62 with another of a different length. One skilled in the art
would be able to determine the length and variations required in
the linkages to obtain a desired amount of asymmetry to avoid
screech modes. A worker in the art would be able to design
appropriate linkages to make the selected components.
Alternately, FIG. 6 illustrates the linkages 60 and 62 may be equal
in length and an additional actuator 64 may be provided. The
flameholders 54 and the linkages 60 are attached to the first
actuator 58 and the flameholders 56 and the linkages 62 are
attached to the additional actuator 64. The actuators 58 and 64 are
configured to rotate the associated flameholders 54 and 56 by
different amounts than each other.
Turbine engines 10 primarily use augmented airflow at take-off or
to assist the aircraft in obtaining supersonic speeds.
Additionally, the altitude and airspeed of the aircraft when
augmentor operation begins during flight may vary. When the
aircraft is operating at low altitudes but high speeds the force
required to rotate the flameholders 54 and 56 is increased.
However, the low altitude and high speed create ideal conditions
for combustion within the exhaust nozzle 24 and less wake width of
the flameholders 54 and 56 is required. The actuators 58 and 64 and
linkages 60 and 62 may be arranged to rotate the flameholders 54
and 56 a partial amount to create the necessary wake width but
without requiring the actuators 58 and 64 to exert undue force.
Alternately, high altitudes and low speeds create much lower
pressure within the exhaust nozzle 24. The force required to rotate
the flameholders 54 and 56 is decreased. However, the lower
pressure in the exhaust nozzle 24 requires more wake width by the
flameholders 54 and 56 to assist combustion. Therefore, the
actuators 58 and 64 and linkages 60 and 62 may be arranged to
rotate the flameholder 42 a greater amount to create larger wakes
in this situation.
Although a preferred embodiment of this invention has been
disclosed, a worker of ordinary skill in this art would recognize
that certain modifications would come within the scope of this
invention. For that reason, the following claims should be studied
to determine the true scope and content of this invention.
* * * * *